Energy
Energy Stores:
• A store is the way the energy is stored in a system. There are eight types.
o Kinetic o Gravitational potential
o Magnetic o Elastic Potential
o Chemical o Nuclear
o Electrostatic o Light
o Thermal internal
• Throwing an object upwards – when you throw a ball upwards, just after the ball leaves your and it has
a store of kinetic energy. When the ball reaches its highest point, it has a store of gravitational
potential energy. Just before you catch it again, it has a store of kinetic energy.
• Boiling water in a kettle – thermal energy increases electrical energy decreases.
• Burning coal – thermal energy increases chemical energy decreases
• A car using brakes to slow down – thermal energy increases kinetic energy decreases.
• Dropping an object which does not bounce – kinetic energy decreases and thermal energy increases.
• Throwing a ball with a constant force – kinetic energy increases chemical energy decreases.
• Holding two magnets with north poles facing – kinetic energy increases magnetic energy decreases.
• A kJ is 1000 joules and a J is 1000kJ.
• The principle of the conservation of energy ~ energy is not created or destroyed, it is transferred from
one store to another.
• Energy losses from a system – despite principle of the conservation of energy we can’t recover all
energy used.
Elastic Potential energy:
• Hooks Law
o When an elastic object is stretched, the increased length is called its extension. The extension
of an elastic object is directly proportional to the force applied to it.
o F = k x e (Force (N) = spring constant (N/m) x extension (m))
• If an object returns to its normal shape after being stretched or squashed it is considered to be elastic.
• When an object is stretched, it stores elastic potential energy.
• Ee = ½ ke² (elastic potential energy (J) = ½ x spring constant (N/m) x extension² (m))
Kinetic Energy:
• Energy stored by a moving object e.g. the energy it has from moving.
• When we make an object move from zero velocity to a new velocity work is done – this work is the
kinetic energy.
• Kinetic energy depends on how heavy an object is – the heavier it is the harder it is to move and how
fast the object will get – getting faster takes more energy.
• E = ½ mv² (kinetic energy (J) = ½ x mass (kg) x velocity² (m/s))
Gravitational Potential Energy:
Energy Stores:
• A store is the way the energy is stored in a system. There are eight types.
o Kinetic o Gravitational potential
o Magnetic o Elastic Potential
o Chemical o Nuclear
o Electrostatic o Light
o Thermal internal
• Throwing an object upwards – when you throw a ball upwards, just after the ball leaves your and it has
a store of kinetic energy. When the ball reaches its highest point, it has a store of gravitational
potential energy. Just before you catch it again, it has a store of kinetic energy.
• Boiling water in a kettle – thermal energy increases electrical energy decreases.
• Burning coal – thermal energy increases chemical energy decreases
• A car using brakes to slow down – thermal energy increases kinetic energy decreases.
• Dropping an object which does not bounce – kinetic energy decreases and thermal energy increases.
• Throwing a ball with a constant force – kinetic energy increases chemical energy decreases.
• Holding two magnets with north poles facing – kinetic energy increases magnetic energy decreases.
• A kJ is 1000 joules and a J is 1000kJ.
• The principle of the conservation of energy ~ energy is not created or destroyed, it is transferred from
one store to another.
• Energy losses from a system – despite principle of the conservation of energy we can’t recover all
energy used.
Elastic Potential energy:
• Hooks Law
o When an elastic object is stretched, the increased length is called its extension. The extension
of an elastic object is directly proportional to the force applied to it.
o F = k x e (Force (N) = spring constant (N/m) x extension (m))
• If an object returns to its normal shape after being stretched or squashed it is considered to be elastic.
• When an object is stretched, it stores elastic potential energy.
• Ee = ½ ke² (elastic potential energy (J) = ½ x spring constant (N/m) x extension² (m))
Kinetic Energy:
• Energy stored by a moving object e.g. the energy it has from moving.
• When we make an object move from zero velocity to a new velocity work is done – this work is the
kinetic energy.
• Kinetic energy depends on how heavy an object is – the heavier it is the harder it is to move and how
fast the object will get – getting faster takes more energy.
• E = ½ mv² (kinetic energy (J) = ½ x mass (kg) x velocity² (m/s))
Gravitational Potential Energy:
